Prime RingProblem素环问题（深搜dfs）

Prime RingProblem素环问题

Problem Description

A ring is composeof n circles as shown in diagram. Put natural number 1, 2, ..., n into eachcircle separately, and the sum of numbers in two adjacent circles should be aprime.
Note: the number of first circle should always be 1.

环是组合成n个圆圈所示的图。把自然数1，2，...，n为进分别各圈，和数字中的两个相邻圈之和应该是一个素数。

注意：第一圈的数量始终应为1。

Input

n (0 < n <20).

Output

The output formatis shown as sample below. Each row represents a series of circle numbers in thering beginning from 1 clockwisely and anticlockwisely. The order of numbersmust satisfy the above requirements. Print solutions in lexicographical order.
You are to write a program that completes above process.
Print a blank line after each case.

输出格式如下图所示的样品。每一行代表一个系列的圆形数字的环从1开始顺时针和按逆时针方向。号的顺序，必须满足上述要求。在字典顺序打印解决方案。

请你写一个程序，完成上述过程。

打印每个案例后，一个空行。

Sample Input

6

8

Sample Output

Case 1:

1 4 3 2 5 6

1 6 5 2 3 4

Case 2:

1 2 3 8 5 6 7 4

1 2 5 8 3 4 7 6

1 4 7 6 5 8 3 2

1 6 7 4 3 8 5 2

#include
#include 
#include
int nums[10001];
int vis[10001];
int n;
int isPrime(int num)
{
	if(num==1||num==0)
	 return 0;
	for(int i=2;i<=num/2;i++)
	{
		if(num%i==0)
		{
		//	printf("xxx");
			return 0;
		}
		 
	}
	return 1;
}
void dfs(int step)
{
	if(step==n+1)
	{
		int j;
		for(j=1;j